Apparatus for measuring the electric current



J. R. FINNEY. Apparatus for Measuring the Electric Current. No. 231,415.

Patented Aug. 24,1880.

wceulm.

N. PETERS PHOTD-LITHOGRAFHER, WASHINGTON, D C.

UNITED STATES PATENT 'OFFIGE.

JOSEPH R. FINNEY, OF PITTSBURG, PENNSYLVANIA.

APPARATUS FOR MEASURING THE ELECTRIC CURRENT.

SP EGIFIGAT ION forming part of Letters Patent No. 231,415, dated August24, 1880,

Application filed November 7, 1879.

To all whom it may concern:

Be it known that I, J osnrn R. FINNEY, of Pittsburg, in the county ofAllegheny and State of Pennsylvania, have invented a new and usefulImprovement in Apparatus for Measuring and Registering the Force of theElectric Current and 1 do hereby declare the following to be a full,clear, and exact description of my new and improved apparatus formeasuring and registering the force of the current of dynamicelectricity generated by a galvanic battery or by an electromagneticinduction-machine.

In devices hitherto used for measuring the force ofthe voltaic ormagneto-electric current, such as galvanometers and voltameters, thestrength or dynamic force of the current only is indicated, togetherwith the variation in intensity of the current from time to time.

The object of my invention is toadvance a step farther in themeasurement of the electric current by taking account not only of theforce of the current, but also of the time during which it is operated,and thus by including in the measurement the combined force and time toobtain a measure of the quantity of electric current employed for anygiven purpose. By this means it will be easy to ascertain the quantityof electric current used to run a machine or to operate an electriccandle.

To enable others skilled in the art to construct and use my improveddevice for measuring the electric current, I will proceed to describeits construction and operation.

In the accompanying drawings, Figure l is a front or face view of mymeasuring device.

Fig. 2 is an end view. Figs. 3 and 4 are side views from opposite sides.Fig. 5 is a section through the circuit-breaker, showing the operationof the armature to operate the registering device.

In the several figures like letters indicate the same parts.

My invention consists in the combination of an automatic circuit-breakerwith clock-work gearing and dial-plates and a balance-wheel or governor,the effect of this combination being that the circuit-breaker (operatedby the electric current to be measured) gives motion to the clock-workgearing which is more or less rapid, according to the varying force orintensity of the current, the balance-wheel or governor checks theotherwise too rapid motion of the circuit-breaker, and the hands anddialplates record the aggregate number of volts (or other unit ofelectrodynamic force) employed by the electric machineor electric light,850., to which my device is applied.

In the accompanying drawings, a is the front plate, and b the backplate, connected together by four corner-posts, c c c c, which togetherconstitute the frame of the machine.

At one end of the frame is placed the electro-magnet d of thecircuit-breaker, which is attached to the frame by the screw 0, but isinsulated from the plate I), on which it rests, by a rubber plate, f,and bushing g for the screw 0.

The cores h h of the eleetro-magnet are surrounded by the wire-coiledspools s s in the usual way.

The armature "i of the circuit-breaker is pivoted to a bracket, j,attached to the front plate, a, of the frame, so that the armature isimmediately over the two poles of the electro-magnet.

The adjustable contact-screw 7c is inserted through the front plate, a,so that its point is over the armature, which is pressed up against thepoint of the contact-screw It by the spring I.

The wire 2 from one of the poles of the battery. (or electromagneticmachine, as the case may be,) which generates the electric current, isconnected with the screw 6, which is insulated from the frame of themachine, as before described, and shown in Fig. 5, and thereby forms anelectric connection with the cores h h of the electro-magnet of thecircnitbreaker. The wire z is also connected with one of the helices ofthe electro-magnet d of the circuitbreaker, and the wire 2 from theother end of the helices is connected with the frame-work of themachine, which is electrically connected with the ground or with theother pole of the battery.

By this arrangement of the wires and connection with the battery (whichis shown in Fig. 2) the electric current is continuously flowing fromone pole of the battery by the Wire 2 through my apparatus to the otherpole of the battery, or to the ground by the wire z.

When the armature 'i is held away from the poles of the electro-magnet dand forced against the contact-screw k by its spring I, as in Fig. 2,the electric current passing through the helices around the cores It Itmagnctizes them, and they immediately attract the armature i; but assoon as the armature touches the cores h h the electric current, seekingthe path of least resistance, instead of passing through thehelicesofthe electro-magnet, flows through the cores h h, and through thearmature which is connected with the other pole of the battery, or withthe ground, as hereinafter explained. As soon as the electric currentleaves the helices and finds its way through the cores h it they aredemagnetized, and the armature i, being no longer held by the attractivepower of the magnet, yields to the pressure of its spring I, which atonce raises it from the poles of the magnet, and, breaking the contactwith the armature, restores the circulation of the current through thehelices aml again magnetizes the cores which attract the armature. Thisalternate magnetizing and demagnetizing of the cores h h of thecleetro-magnet ot' the circuit-breaker would cause a continuousvibration of the armature between the poles of the electro-magnet andthe contact-screw, which would be extremely rapid were it not otherwisechecked and regulated, as hereinafter described.

There is another mode of connecting my device with the poles of thebattery, (shown in Fig. 6,) which has the advantage (where a branchcurrent only is carried through my measuring device, ashereinafterexplained) of expending only half as much of the electriccurrent as is necessary by the arrangement just described.

The only difference in construction of the apparatus shown in Figs. 2and 6 is that in Fig. 2 the contact-screw I: is in electrical connectionwith the frame of the machine, sothat the electric current is constantlyflowing through my measuring-machinc, while in Fig. 6 the contact-screwk is insulated from the frame of the machine by a bushing, a, madeofindia-rubberor other non conductor. When thus constructed, and asshown in Fig. 6, the contact-screw k is connected with one pole of thebattery by the wire (J, the armature i of the circuit-breaker isconnected by wire 3 with the helices of the electromagnet (I, the otherextremity of the helices being connected with the ground. By thisarrangement, when the spring lot the armature presses it against thecontact-screw k the electric circuit is complete, the current flowsthrough screw k, armature i, electro-magnet (l to the ground at G; butas soon as this takes place the cores h ll, becoming magnetized, attractthe armature i, destroy the contact with the screw It, and, breaking thecircuit, demagnetize the cores h h of the electro-magnet, which nolonger hold the armature, but allow it to be carried up by its springinto contact with the screw it, by which the current is restored and thearmature again attracted. By this plan it will be noticed that when thecontact of the armature i with the screw it is broken no current passesthrough my apparatus, as the screw is not in electrical connection withany part of the mechanism.

I will now proceed to describe how the vibration of the armatureoperates the devices for indicating the number of these vibrations.

The vibrating arm of the armature i, which is pivoted to the bracket j,as beforedeseribcd, is extended back of its pivotal point, and to itsrear end is attached a pawl, 0, which takes into the teeth of aratchet-wheel, m, (see Fig. 4,) so that at each vibration of the leveror arm of the armature i the ratchet-wheel is turned the distance of onetooth.

The lever-arm of the armature 'l is rigidly attached to a horizontalshaft, n, which has its hearings in the bracket j, and forms the pivotor turning-point of the armature i, so that as the armature is vibratedthe shaft turns back and forth on its axis.

011 one extremity of the shaft n is loosely attached a balance-wheel, p,which regulates the motion of the shaft, and consequently the vibrationsof the armature.

A hair-spring, r, is connected with the balance-wheel aml shaft, oneextremity being attached to the shaft and the other to one of the spokesof the balance-wheel. As the balancewheel is loosely attached to theshaft, it can vibrate through a larger are of a circle than the shaft,the vibration of the shaft beinglimited by the vibration of the armaturewith which it is rigidly connected, and the vibration of the armaturebeing limited by the contact-screw/c. By means of this arrangement thebalance-wheel and its hair-spring control the vibration of the shaft,makingit very much slower than it otherwise would be; but the controleffected by the balance-wheel is not absolute, but is etfected by theforce applied by means of the electric current to the armature, so thatas the force of the current increases the balance-wheel vibrates morerapidly, and, vice versa, the force of the current diminishes thebalance-wheel vibrates more slowly. The connection of the balance-wheeland the shaft through the intervention of the hairspring compels theshaft to vibrate with the balance-wheel, though through a shorter are,as before stated, and therefore every vibration of the armature causesthe ratchet-wheel m to turn on its axis the distanceof one tooth.

It will thus be seen that so long as the electric current is flowingthrough the measuring apparatus the ratchet-wheel m continues to rotateon its axis more or less rapidly in exact proportion to the intensity ofthe current. It only remains to record this rotation of theratchet-wheel by means of the connected clockgearin 0n the shaft q ofthe ratchet-wheel m is a short screw, t, which gears into the teeth of acog-wheel, u, the shaft of which is at right angles to the shaftq of theratchet-wheel m.

The shaft azof the cog-wheel a extends through the front plate, g, andhas a hand, w, attached to it which revolves with its shaft 00 around adial-plate which is properly graduated.

On the shaft :0 is a pinion, c, which meshes into a cog-wheel, it,having ten times as many teeth as the pinion c. The shaft of this secondcog-wheel u also extends through the front plate, a, and is furnishedwith a hand, w, which revolves once for every ten revolutions of thehand 10 and indicates its revo1u-.. tions on its dial. A pinion, n, onthis shaft u gears into a third cog-wheel, a, on a shaft, or, which alsohas a hand, w, and dial, and so on, there being as many series ofcogwheels, pinions, shafts with hands, and dialplates as may be desired,each hand making one revolution around its dial for every tenrevolutions of the hand on the next preceding dial, and thus indicatingin units, tens, hundreds, and thousands, 850., the unit of measurementof the electric force employed.

In applying the mechanism which I have described to the measurement ofthe force and quantity of the electric current employed by any electricmachine, electric light, or other apparatus operated by galvanism ordynamic electricity, a difficulty occurs in the fact that my measuringmechanism operates by means of an automatic circuit-breaker, and thatthe alternate closing and breaking of the circuit would, if the entirecurrent passed through my mechanism, break the continuity of the currentand interfere with the operation of the machinery or the continuity ofthe light if applied to an electric candle. To obviate this difficulty Ido not permit the entire electric, current to pass through my measuringmechanism, nor, indeed, any part of the current which operates themachinery or electric candle but instead of this I divert from the maincurrent a small portion of the current, which deflected current I passthrough my measur ing mechanism and thence to the ground. Thisarrangement is shown in Fi 6, in which A is the main-line wire; B, thebattery (if a battery be used or other source of the electric current.To this main wire A, I connect a branch wire, 0, which is connected withthe frame of my measuring mechanism, and is in electric connection withthe contact-screw 7c of the circuit-breaker. A wire, 3 connects thearmature i of the circuit-breaker with one of the helices of theelectro-magnet d while the other extremity of the wire runs to theground at G.

In order to prevent the entire current from the battery running throughmy measuring apparatus to the ground at G, instead of passing along themain wire A to do its required work, I interpose a resistance-coil, R,in the branch wire (3, between the main wire A and my measuringmechanism. The number of ohms of resistance of the resistance device Bbeing known, the proportion which the deflected current passing off bythe branch wire 0 bears to the whole current of the battery B is easilyascertained, and therefore the amount of current registered by mymeasuring-instrument will bear the same proportion to the residue of thecurrent which passes on over the main wire A,and is not deflected topass through my measuring mechanism.

The dial-plates on my measuring apparatus should be marked withreference to the resistance of the resistance device B, so as toindicate at once the force of the current passing over the main wire Aless the small current deflected through the branch wire 0 to operate mymeasuring mechanism.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. The method hcreinbefore described of ascertaining and registering theforce and quantity of the electric current by applying the 0perativeforce of the current to a balance-wheel, so that the irregularities ofits motion or variations from isochronism shall, by means of connectedgearing, indicate the corresponding variations of the current,substantially as set forth.

2. The combination, with the vibrating arm of an automaticcircuit-breaker, of a balancewheel loosely attached to the pivotal shaftof the armature and a hair-spring attached at one end to thearmature-shaft and at the other end to the balance-wheel, substantiallyas and for the purpose described.

In testimony whereof I, the said J OsEPH R. FINNEY, have hereunto set myhand.

JOSEPH R. FINNEY.

Witnesses:

A. O. JOHNSTON, R. O. WRENSHALL.

